1. Field of the Invention
The invention concerns a cooling device for arrangement between two gradient coil windings of a gradient coil for dissipation of the heat (arising upon current being fed to the gradient coil windings) by means of a coolant flowing through one or more coolant channels in the cooling device.
2. Description of the Prior Art
Gradient coils have in a known manner, a number of conductor structures cast in a resin matrix (for the most part epoxy resin) that are fed with current to generate spatially-resolved three-axis magnetic fields. Gradient currents of several hundred amperes at voltages of up to 2 kV are typical and lead to power losses of 10 kW and more, and must be dissipated in the form of heat. Cooling devices are therefore cast in the coil that are embedded between the individual coil supports in order to be able to discharge the dissipated power as effectively as possible. The thermal resistance between the heat sources (thus the gradient coil windings) and the heat sinks (thus the coolant medium) should be optimally slight, which is why the distance from the cooling devices to the coil conductors should be as small as possible given an optimally large heat exchanger area.
A known cooling device has a thin supporting plate on which meandering cooling tubes with round cross-section are wound. The cooling tubes, of which several hundred meters are typically required in a number of parallel cooling circuits per coil, must be manually conducted through bores in the support plate and fixed until knotted waxed silk cords. The cooling tubes are laid such that the tube ends for the water inlet and outlet are placed directly next to one another, and are set at the corresponding connection parts after encasing of the entire gradient coil.
The manual connection of the cooling tubes with the support plate is very complicated and time-consuming and thus expensive. Moreover, due to the round tube cross-section only a linear contact to the heat-generating copper conductor winding (with correspondingly poor heat transfer) results.